/* Shared site chrome: header nav, return-home button, footer, page hero.
   Pulled out of the per-page inline <style> blocks so every page stays in sync. */

body { opacity: 1 !important; visibility: visible !important; }
.preloader { display: none !important; }

/* HEADER NAVIGATION */
.navbar-header { float: left; }
.navbar-nav { margin-top: 12px; margin-bottom: 0; }
.navbar-nav li a {
    border: 1px solid #333 !important;
    padding: 8px 18px !important;
    margin-left: 10px;
    margin-right: 10px;
    border-radius: 4px;
    transition: background-color 0.3s ease, color 0.3s ease;
    text-transform: uppercase;
    font-size: 12px;
    font-weight: 700;
    color: #333 !important;
    background: transparent;
}
.navbar-nav li a:hover {
    background: #333 !important;
    color: #fff !important;
}
.navbar-nav li.active a,
.navbar-nav li a[aria-current="page"] {
    background: #333 !important;
    color: #fff !important;
}

/* RETURN-HOME BUTTON (sub-pages only) */
.btn-return-home {
    display: inline-block;
    margin-top: 12px;
    padding: 8px 20px;
    border: 2px solid #333;
    background: #333;
    color: #fff !important;
    border-radius: 4px;
    font-weight: 700;
    text-transform: uppercase;
    font-size: 12px;
    transition: background-color 0.3s ease, color 0.3s ease;
}
.btn-return-home:hover {
    background: transparent;
    color: #333 !important;
    text-decoration: none;
}
.btn-return-home i { margin-right: 8px; }

/* Keep the mobile nav dropdown above page content on every page */
#main_menu {
    position: relative;
    z-index: 100;
}
.main_menu_bg {
    overflow: visible !important;
}

/* Visible keyboard focus for every interactive element */
a:focus-visible,
button:focus-visible {
    outline: 2px solid #333;
    outline-offset: 2px;
}

/* PAGE HERO (Projects, Events) */
.main-page-header {
    padding: 80px 0 40px;
    text-align: center;
    background: #fdfdfd;
    border-bottom: 1px solid #eee;
}
.main-page-header h1 {
    font-weight: 700;
    font-size: 32px;
    text-transform: uppercase;
    letter-spacing: 3px;
    color: #222;
    margin: 0;
}
.main-page-header .underline {
    width: 60px;
    height: 4px;
    background: #333;
    margin: 20px auto 0;
}
.main-page-header p {
    max-width: 60ch;
    margin: 20px auto 0;
    color: #666;
    font-size: 15px;
}

.footer { padding: 40px 0; border-top: 1px solid #eee; }

/* Math blocks (Research/Talks pages) shouldn't force page-wide horizontal scroll on mobile */
.katex-display {
    overflow-x: auto;
    overflow-y: hidden;
}

/* Compact header bar + tighter dropdown gap on mobile so the menu doesn't eat the fold */
@media (max-width: 768px) {
    .main_menu_bg {
        height: 70px;
    }
    .main_menu_bg .nave_menu {
        margin-top: 12px;
    }
    .navbar-default .navbar-collapse {
        margin-top: 12px !important;
    }
    /* This theme's bootstrap.min.css was stripped of the stock mobile
       .navbar-nav unfloat rule, so the menu stayed right-floated and
       narrow instead of a full-width stacked panel. */
    .navbar-header {
        float: none;
    }
    .navbar-nav {
        float: none !important;
        margin: 0;
    }
    .navbar-nav > li {
        float: none;
    }
    .navbar-nav li a {
        margin-left: 0;
        margin-right: 0;
        margin-bottom: 8px;
        display: block;
        text-align: center;
    }
    /* Open panel doesn't push page content down (fixed-height header +
       overflow:visible), so give it full viewport height while open —
       otherwise its white background falls short and page content
       peeks out underneath it. Scoped to mobile + .in (open) only: a
       global rule here previously painted an opaque full-width panel
       over the desktop return-home button. */
    .navbar-collapse.in {
        background-color: #ffffff !important;
        position: relative;
        z-index: 101;
        min-height: 100vh;
        max-height: 100vh;
    }
}

@media (prefers-reduced-motion: reduce) {
    * {
        transition-duration: 0.01ms !important;
        animation-duration: 0.01ms !important;
    }
}